CASCADE reproduction artifacts: per-sample decision records, evaluation corpus and analysis scripts

Reproduction artifacts for the CASCADE study of a layered local defense for MCP-based systems. Contains per-sample decision records for all three evaluated configurations (5,000 records each), the frozen evaluation corpus, the intermediate collection bundle documenting external provenance, the Layer 2 reference texts, the analysis scripts that regenerate every table in the paper, and a verification script that recomputes every confusion matrix, interval and count reported there before reporting success. The three result files are row-aligned and must be joined by row index rather than by sample_id, which is not unique. See README.md.